A power cell of an internal combustion engine generally comprises a reciprocating piston disposed within a cylindrical cavity of an engine block, and a connecting rod which joins a lower portion of the piston to a crankshaft. One end of the cylindrical cavity may be closed while another end of the cylindrical cavity may be open. The closed end of the cylindrical cavity and an upper portion or crown of the piston defines a combustion chamber. The open end of the cylindrical cavity permits oscillatory movement of the connecting rod, which is typically linked to the piston by a piston pin that is received within a piston pin bore defined by the piston. The crankshaft converts linear motion of the piston (resulting from combustion of fuel in the combustion chamber) into rotational motion.
Engines, and in particular the power cell assemblies, are under subject to constant efforts to increase overall efficiency, e.g., by reducing weight of the power cell assemblies and/or increasing pressures and temperatures associated with engine operation. As noted above, known power cell designs have typically employed a piston pin that is inserted into the pin bore of the piston, thereby retaining the connecting rod to the piston body. Moreover the piston pin allows the connecting rod to pivot with respect to the piston body as the piston reciprocates within the power cylinder during engine operation. However, the piston pin increases overall weight and complexity of the power cell assembly. While some power cell designs are known that eliminate the piston pin, known solutions suffer from drawbacks such as an inefficient transfer of reciprocal motion of the piston to rotational motion of the crankshaft, instability in the joint, or necessitate a complex assembly of the power cell.
Accordingly, there is a need for a more robust, lightweight power cell design that offers reduced overall weight, e.g., by eliminating the piston pin, while providing a stable and efficient connection between the connecting rod and the piston body.